抄録
The optimization study on the fluctuating punted kick was carried out. It was found from the wind tunnel tests that the side force coefficient depended on the position of the lace of the ball. It has the positive and negative values. That becomes the key to fluctuate the ball during the flight. What are the features of the optimal punted kick in rugby? The objective of this paper is to provide the answers to these questions by optimizing the initial velocity and angular velocity vectors as well as the initial Euler angles for the punted kick. Three objective functions are considered, two of which are the number of extrema in the forward and the lateral directions. The third objective function is the hang time. For optimization all the objective functions must be maximized. The optimization was carried out by using an elitist non-dominated sorting genetic algorithm. The results are summarized as follows: in order to make the hang time longer, the initial pitch angle should be about 90° like a rocket. In the phase of rising, the smaller angle between the longitudinal axis of the ball and the direction of the flight path is preferable. In the phase of falling, the larger angle is preferable. In order to fluctuate the ball more frequently, the spin should be given to change the direction of the side force.
